| Abstrakt: |
The steadily growing demand for fertilizers and increasing interest for organic inputs result in rapid expansion and diversification of the solid nitrogen (N) fertilizer market. Fertilizer legislations distinct different fertilizers classes (i.e. organic, organo-mineral, inorganic), but standards and norms related to nutrient- and carbon origin remain dynamic and lag behind. This, together with poor analytical understanding of commercially available N sources leaves many open questions to industries and farmers, fostering increased prevalence of fertilizer adulteration and false claims on the organic fertilizer market. This work presents a thorough, science-based multivariate assessment on a wide sample set (n = 52) of the solid N fertilizer market, including multiple state-of-the-art analytical attributes, such as stable isotopes of nitrogen and carbon. Results present the possibility to correctly (94%) classify N fertilizers using multivariate fingerprinting with linear discriminant analysis. We extract analytical cut-off values for discriminants indicative for ingredient origin and conclude that, when a fertilizer has (i) a bulk δ15N below 2‰; and (ii) a relatively high total N content (> 15%), from which (iii) a high share (> 50%) is water soluble (i.e. in ammonium or nitrate form), it is extremely unlikely to be of pure biologic origin. We also present additional analyses (e.g. amino acids, peptide sequences, δ13C of specific compounds, and stable isotopes of boron) that can then be used to further trace down the N sources in novel fertilizer products. This work contributes to future debates, regulations, and further development of analytical standards for solid N fertilizers, possibly to be used in fraud detection. [ABSTRACT FROM AUTHOR] |
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